Remove obviously unneeded forward declarations from headers under src/{app,base,net}.

net/http/http_network_transaction.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_HTTP_HTTP_NETWORK_TRANSACTION_H_
 #define NET_HTTP_HTTP_NETWORK_TRANSACTION_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
 #include "base/ref_counted.h"
 #include "base/scoped_ptr.h"
 #include "base/time.h"
 #include "net/base/net_log.h"
 #include "net/base/request_priority.h"
 #include "net/base/ssl_config_service.h"
 #include "net/http/http_auth.h"
 #include "net/http/http_response_info.h"
 #include "net/http/http_transaction.h"
 #include "net/http/stream_factory.h"
 #include "net/proxy/proxy_service.h"
 
 namespace net {
 
-class ClientSocketFactory;
-class ClientSocketHandle;
 class HttpAuthController;
 class HttpNetworkSession;
-class HttpRequestHeaders;
 class HttpStream;
 class HttpStreamHandle;
-class HttpStreamRequest;
 class IOBuffer;
 
 class HttpNetworkTransaction : public HttpTransaction,
                                public StreamFactory::StreamRequestDelegate {
  public:
   explicit HttpNetworkTransaction(HttpNetworkSession* session);
 
   virtual ~HttpNetworkTransaction();
 
   // HttpTransaction methods:
@@ skipping 197 matching lines @@
   bool establishing_tunnel_;
 
   DISALLOW_COPY_AND_ASSIGN(HttpNetworkTransaction);
 };
 
 int ConvertRequestPriorityToSpdyPriority(RequestPriority priority);
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_NETWORK_TRANSACTION_H_